~50% to 70% of original size. The Verdict: Legacy format. Useful for older emulators on low-power devices (original XBox, PSP with Nintendont).
Modern emulators like Dolphin can read compressed formats natively with zero impact on performance. Best Compression Formats gamecube roms highly compressed
For the best balance of file size and performance, it is recommended to use the RVZ format ~50% to 70% of original size
– Using Dolphin Emulator’s RVZ converter , he compressed the .nkit.iso files. RVZ uses LZMA or zstd, shrinking games like Luigi’s Mansion (1.4 GB → ~260 MB) without losing playability. this junk is preserved
or padding. In a standard raw dump, this junk is preserved, meaning even the smallest games take up the full 1.35 GB of storage on your drive. The Mechanics of Compression